Method and apparatus for promoting droplets coalescense in oil continuous emulsions

ABSTRACT

Separation apparatuses for the separation of a mixture of two fluids, such as a water-in-oil emulsion, via electrocoalescence, are provided. A separation apparatus may include a series of flow conditioners each having a different permittivity, such that the flow conditioner having a permittivity that is similar or equal to the permittivity of the flowing medium is selected. Another separation apparatus may include a flow conditioner having a frequency-dependent permittivity, such that the frequency of the electric field generated is selected so that the permittivity of the flow conditioner is as similar as possible to or equal to the permittivity of the flowing medium. Another separation apparatus may include a replaceable flow conditioner that may be replaced with a flow conditioner having a permittivity that is as similar to or equal to the permittivity of the flowing medium.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of and claims priority from U.S.Non-provisional application Ser. No. 15/888,773 filed Feb. 5, 2018, andtitled “METHOD AND APPARATUS FOR PROMOTING DROPLETS COALESCENCE IN OILCONTINUOUS EMULSIONS,” a copy of which is incorporated by reference inits entirety for purposes of U.S. patent practice.

BACKGROUND Field of the Disclosure

The present disclosure generally relates to separation of fluids. Morespecifically, embodiments of the disclosure relate to the separation ofan emulsion by promoting droplets coalescence using a controllableelectrostatic field and adaptive permittivity.

Description of the Related Art

Produced hydrocarbons (such as crude oil) may contain water as well asother fluids. Consequently, the separation of water from oil is requiredin hydrocarbon processing to produce saleable products.Electrocoalescence for water-oil separation has been known for over ahundred years and the technology is now widely implemented in commercialapplications. For example, electrocoalescers are installed in existingoil and gas production facilities around the world. Coalescer packingsare also deployed in the oil and gas industry inside separator vesselsto enhance the coalescence process but such packings typically do notwork in synergy with an electrostatic field. In electrocoalescence, thedroplet coalescence is believed to be triggered by the electric field ifthe droplets are very close to each other. At distances larger than afew droplet diameters, the electrostatic forces may not drive theapproach and collision of the droplets, as the electrostatic forces thatgenerate droplets' attraction are strongly dependent on theinter-droplets distance. Within the limitations of industrial equipmentdesign, the electrostatic forces may be too inefficient to promote thedroplets coalescence when the distance between droplets is equal to orgreater than the droplet diameter.

SUMMARY

To address limitations with electrocoalescers, some prior art techniquesintroduce a flow disrupting element to prevent the droplet alignment andarching that would be driven by the electric field in a laminar flow.For example, U.S. Pat. No. 9,440,241 describes the advantage ofintroducing a flow disrupting element to enhance micro-turbulence andelectrocoalescence between electrodes of a separation device. However,such prior art techniques fail to consider that turbulence is not themain flow characteristic that enhances the droplets contact rate. Insome instances, increasing turbulence intensity locally with such a flowdisrupting element may result in droplets breaking-up (that is, fluidsre-mixing) and negatively impact separation. In contrast to the priorart techniques, the curvature of emulsion flow streamlines and thesplitting and merging of stream-tubes can be the primary drivers ofoptimized droplets contact rate and contract time. Furthermore, suchprior art techniques fail to consider any effect of the dielectricconstant (that is, permittivity) of the flow disrupting element versusthe dielectric constant of the water-oil-emulsion being separated.

Embodiments of the present disclosure improve electrocoalescerseparation performance by designing and adjusting the dielectricproperties of flow conditioner elements and maintaining the electricfield at an optimal value. Embodiments of the disclosure further includean improved geometry of a flow conditioner to further improve efficiencyof the separation process.

In one embodiment, an apparatus for the separation of a mixture of twoliquids is provided. The apparatus includes a section configured toreceive a mixture of two liquids and a first flow conditioner sectiondownstream of the section, the first flow conditioner section having atleast one first electrode for generating a first electric field and afirst flow conditioner having a first permittivity. The apparatus alsoincludes a second flow conditioner section downstream of the first flowconditioner section and having at least one second electrode forgenerating a second electric field and a second flow conditioner havinga second permittivity. The apparatus further includes a permittivitymeasurement apparatus coupled to the first section and configured tomeasure the permittivity of the mixture and a flow conditioner sectionselector configured to receive the mixture permittivity from thepermittivity measurement apparatus and energize the at least one firstelectrode of the first flow conditioner section or energize the at leastone second electrode of the second flow conditioner section based on acomparison between the mixture permittivity and the first permittivityand the mixture permittivity and the second permittivity.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the first flow conditioner is a helicoidal-shaped flowconditioner having a helicoidal flow path or a branched flow conditionerthat includes a plurality of branched flow paths. In some embodiments,the second flow conditioner is a helicoidal-shaped flow conditionerhaving a helicoidal flow path or a branched flow conditioner thatincludes a plurality of branched flow paths. In some embodiments, thefirst flow conditioner is an inorganic material and a polymeric matrix.In some embodiments, the second flow conditioner is an inorganicmaterial and a polymeric matrix. In some embodiments, a length of thefirst flow conditioner and a strength of the first electric field areselected such that the electroviscous number of the flow conditionersection is in the range of 1000 to 600000.

In another embodiment, a method of separating a mixture of two liquidsvia electrocoalescence is provided. The method includes providing themixture to a separation apparatus. The separation apparatus includes afirst flow conditioner section that includes at least one firstelectrode for generating a first electric field and a first flowconditioner having a first permittivity and a second flow conditionersection that includes at least one second electrode for generating asecond electric field and a second flow conditioner having a secondpermittivity. The method further includes measuring the permittivity ofthe mixture, and comparing the mixture permittivity to the firstpermittivity and the second permittivity. The method also includesenergizing the at least one first electrode of the first flowconditioner section or the at least one second electrode of the secondflow conditioner section based on the comparison, such that only thefirst electric field or the second electric field is generated, anddirecting the mixture through the first electric field or the secondelectric field.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the first flow conditioner is a helicoidal-shaped flowconditioner having a helicoidal flow path or a branched flow conditionerthat includes a plurality of branched flow paths. In some embodiments,the second flow conditioner is a helicoidal-shaped flow conditionerhaving a helicoidal flow path or a branched flow conditioner thatincludes a plurality of branched flow paths. In some embodiments, alength of the first flow conditioner and a strength of the firstelectric field are selected such that the electroviscous number of theflow conditioner section is in the range of 1000 to 600000. In someembodiments, the method includes transmitting the measured permittivityto a flow conditioner section selector configured to energize the atleast one first electrode of the first flow conditioner section orenergize the at least one second electrode of the second flow conditionsection.

In some embodiments, another apparatus for the separation of a mixtureof two liquids is provided. The apparatus includes a first sectionconfigured to receive the mixture, a permittivity measurement apparatuscoupled to the first section and configured to measure the permittivityof the mixture, a flow conditioner section that includes an electrodefor generating an electric field and a flow conditioner having apermittivity range, such that the permittivity range is a function ofthe frequency of the electric field. The apparatus also includes afrequency selector configured to receive the mixture permittivity fromthe permittivity measurement apparatus and energize the electrode of theflow conditioner section at a frequency based on a comparison betweenthe mixture permittivity and permittivity range.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the flow conditioner is a helicoidal-shaped flowconditioner having a helicoidal flow path or a branched flow conditionerthat includes a plurality of branched flow paths. In some embodiments,the flow conditioner includes silica nanoparticles in an epoxy resin. Insome embodiments, a length of the flow conditioner and a strength of theelectric field are selected such that the electroviscous number of theflow conditioner section is in the range of 1000 to 600000.

In another embodiment, another method of separating a mixture of twoliquids is provided. The method includes providing the mixture to aseparation apparatus. The separation apparatus includes a permittivitymeasurement apparatus coupled to the first section and configured tomeasure the permittivity of the mixture, a flow conditioner section thatincludes an electrode for generating an electric field and a flowconditioner having a permittivity range, such that the permittivityrange is a function of the frequency of the electric field, and afrequency selector configured to receive the mixture permittivity fromthe permittivity measurement apparatus and energize the electrode of theflow conditioner section at a frequency. The method further includesmeasuring the permittivity of the mixture and comparing the mixturepermittivity to the permittivity range. The method also includesenergizing the electrode of the flow conditioner section at a frequencybased on the comparison between the mixture permittivity andpermittivity range and directing the mixture through the electric field.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the flow conditioner is a helicoidal-shaped flowconditioner having a helicoidal flow path or a branched flow conditionerthat includes a plurality of branched flow paths. In some embodiments,the method includes transmitting the mixture permittivity to a frequencyselector configured to receive the mixture permittivity from thepermittivity measurement apparatus and energize the electrode of theflow conditioner section at the frequency.

In another embodiment, another apparatus for the separation of a mixtureof two liquids is provided. The apparatus includes a first sectionconfigured to receive the mixture and a flow conditioner section thatincludes an electrode for generating an electric field and a firstremovable flow conditioner having a first permittivity, the flowconditioner section configured to receive a second removable flowconditioner having a second permittivity in place of the first removableflow conditioner. The apparatus also includes a permittivity measurementapparatus coupled to the first section and configured to measure thepermittivity of the mixture and compare the mixture permittivity to thefirst permittivity.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the first removable flow conditioner is a helicoidal-shapedflow conditioner having a helicoidal flow path or a branched flowconditioner that includes a plurality of branched flow paths. In someembodiments, the second removable flow conditioner is ahelicoidal-shaped flow conditioner having a helicoidal flow path or abranched flow conditioner that includes a plurality of branched flowpaths. In some embodiments, the first removable flow conditioner is aninorganic material and a polymeric matrix. In some embodiments, thesecond removable flow conditioner is an inorganic material and apolymeric matrix. In some embodiments, a length of the flow conditionerand a strength of the electric field are selected such that theelectroviscous number of the flow conditioner section is in the range of1000 to 600000.

In another embodiment, another method of separating a mixture of twoliquids is provided. The method includes providing the mixture to aseparation apparatus. The separation apparatus includes a flowconditioner section that includes an electrode for generating anelectric field and a first removable flow conditioner having a firstpermittivity, the flow conditioner section configured to receive asecond removable flow conditioner having a second permittivity in placeof the first removable flow conditioner. The method also includesmeasuring the permittivity of the mixture, removing the first removableflow conditioner from the flow conditioner section, and installing thesecond removable flow conditioner in the flow conditioner section. Themethod further includes energizing the electrode of the flow conditionersection and directing the mixture through the electric field.

In some embodiments, the mixture is a water-in-oil emulsion. In someembodiments, the first removable flow conditioner is a helicoidal-shapedflow conditioner having a helicoidal flow path or a branched flowconditioner that includes a plurality of branched flow paths. In someembodiments, the second removable flow conditioner is ahelicoidal-shaped flow conditioner having a helicoidal flow path or abranched flow conditioner that includes a plurality of branched flowpaths

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a graph of volume percentage of water separated vs. separationtime after electrocoalescence (EC) illustrating the results ofexperiments for combinations of flow conditioners and demulsifierdosage;

FIG. 2 is a graph of volume percentage of water separated vs. separationtime after electrocoalescence (EC) illustrating the results ofexperiments for a first configuration of different flow conditioners;

FIG. 3 is a graph of volume percentage of water separated vs. separationtime after electrocoalescence (EC) illustrating the results ofexperiments for a first configuration of different flow conditioners athigher flowrates;

FIG. 4 is a graph of volume percentage of water separated vs. separationtime after electrocoalescence (EC) illustrating the results ofexperiments for a second configuration of different flow conditioners;

FIG. 5 is a graph of volume percentage of water separated vs. separationtime after electrocoalescence (EC) illustrating the results ofexperiments for a third configuration of different flow conditioners;

FIG. 6 is a graph of the permittivity (real and imaginary parts) of awater-in-oil emulsion vs frequency illustrating the frequency-dependentbehavior of the dielectric constant of the water-in-oil emulsion;

FIG. 7 is a graph of permittivity vs. frequency for a water-in-oilemulsion that depicts the effect of the water cut on the permittivity ofthe water-in-oil emulsion;

FIG. 8 is a schematic diagram of a separation apparatus having a seriesof flow conditioners having different permitivities and disposed in aseries of sections of the separation apparatus in accordance with anembodiment of the disclosure;

FIG. 9 is a block diagram of a process for operation of the separationapparatus depicted in FIG. 8 in accordance with an embodiment of thedisclosure;

FIG. 10 is a schematic diagram of a separation apparatus having a flowconditioner with a frequency-dependent permittivity and disposed insection of the separation apparatus in accordance with an embodiment ofthe disclosure;

FIG. 11 is a graph of permittivity vs. frequency for a water-in-oilemulsion that depicts a frequency shift and its effect on permittivityin accordance with an embodiment of the disclosure;

FIG. 12 is a block diagram of a process for operation of the separationapparatus depicted in FIG. 10 in accordance with an embodiment of thedisclosure;

FIGS. 13A and 13B are schematic diagrams of a separation apparatushaving replaceable flow conditioners with having differentpermittivities and disposed in section of the separation apparatus inaccordance with an embodiment of the disclosure; and

FIG. 14 is a block diagram of a process for operation of the separationapparatus depicted in FIGS. 13A and 13B in accordance with an embodimentof the disclosure.

DETAILED DESCRIPTION

The present disclosure will be described more fully with reference tothe accompanying drawings, which illustrate embodiments of thedisclosure. This disclosure may, however, be embodied in many differentforms and should not be construed as limited to the illustratedembodiments. Rather, these embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey thescope of the disclosure to those skilled in the art.

Embodiments of the disclosure include a separation apparatus for theseparation of mixture of two fluids (for example, a water-in-oilemulsion) via electrocoalescence and having a flow conditioner with apermittivity adaptive to the permittivity of the fluid flowing throughthe separation apparatus. As used herein, the term “flowing medium” mayrefer to the fluid flowing through the separation apparatus. As usedherein, a flow conditioner may also be referred to as a “dropletscollider.” As used herein, the term “permittivity” refers to relativepermittivity.

In one embodiment, a separation apparatus includes a measurement sectionand multiple sections having a flow conditioner with a differentpermittivity. The separation apparatus includes a dielectric measurementdevice that measures the permittivity of the flowing medium in themeasurement section of the separation apparatus. The measuredpermittivity may be provided to a section selector that compares themeasured permittivity to the stored permittivities of the flowconditioners and selects a flow conditioner having a permittivity thatis equal to or as similar as possible to the measured permittivity. Thesection selector then energizes the electrodes (via an AC voltagegenerator) of the selected flow conditioner.

In another embodiment, a separation apparatus includes a measurementsection and a section having a flow conditioner with afrequency-dependent permittivity. The separation apparatus includes adielectric measurement device that measures the permittivity of theflowing medium in the measurement section of the separation apparatus.The measured permittivity may be provided to a frequency selector thatselects an electric field frequency that causes the permittivity of theflow conditioner to be equal to or as similar as possible to thepermittivity of the flowing medium. The frequency selector thenenergizes the electrodes (via an AC voltage generator) of the flowconditioner at the selected frequency.

In another embodiment, a separation apparatus includes a measurementsection and a section having a replaceable flow conditioner with firstpermittivity. The replaceable flow conditioner may be replaced with aflow conditioner having a second permittivity. The separation apparatusincludes a dielectric measurement device that measures the permittivityof the flowing medium in the measurement section of the separationapparatus. The measured permittivity may be provided to a computer fordisplay. Based on the measured permittivity, the replaceable flowconditioner may be replaced with the flow conditioner having the secondpermittivity such that the second permittivity is equal to or as similaras possible to the measured permittivity of the flowing medium.

EXAMPLES AND EXPERIMENTS

The following examples and experiments are included to demonstrateembodiments of the disclosure. It should be appreciated by those ofskill in the art that the techniques and apparatuses disclosed in theexamples which follow represent techniques and apparatuses discovered tofunction well in the practice of the disclosure, and thus can beconsidered to constitute modes for its practice. However, those of skillin the art should, in light of the present disclosure, appreciate thatmany changes can be made in the specific embodiments which are disclosedand still obtain a like or a similar result without departing from thespirit and scope of the disclosure.

The examples and experiments described below demonstrate an improvementin separation performance obtained by optimizing the combination of flowconditioner and electric field and further show the influence of thegeometry of the flow conditioner on the optimization. Experiments wereconducted in a flow loop using a positive displacement pump, atemperature chamber hosting the electrodes section and the separationcones (to monitor the separation profiles of the treated emulsionsamples), and a rack having a voltage amplifier, a function generator,an oscilloscope, and laptop as a controller. The computationalsimulation results were obtained using the COMSOL® Multiphysicssimulation manufactured by COMSOL Inc. of Stockholm, Sweden.

The experiments were performed using three different flow conditioners.A highly branched flow conditioner (Type A) was used. As used herein,the term “highly branched” refers to a flow conditioner having multipleflow stream splitting and intersections that maximize inter-dropletcontact. Flow conditioners of Type-A had a characteristic mixing lengthL_(m)=0.4 centimeters (cm)±2 millimeters (mm). A flow conditioner havinga helicoidally shaped mixer (Type B, also referred to as a “helicoidalflow condition”) was also used. Flow conditioners of Type-B had acharacteristic mixing length L_(m)=1.0 cm±2 mm. As used herein, the termcharacteristic mixing length L_(m) is defined as the average hydraulicdiameter of the volume between two successive flow separation wallsthat, arranged in pattern, form the flow conditioner. A “flowconditioner” of Type C was an empty pipe and did not include any flowconditioning elements.

As described herein, the experimental data shows that the flowconditioner geometry affects and may improve the water-oil separationperformance. In particular, the highly branched conditioner (Type-A)improves water-oil separation more than the other conditioner (Type-B).Moreover, both the Type-A and Type-B flow conditioners provedadvantageous over the straight pipe (Type-C). Accordingly, a static flowconditioning element designed to improve droplets collision may improvewater-oil separation over a simple electric field application inside asmooth pipe section as long as the induced turbulence does not lead tore-emulsification.

The electrostatic separation experiments were performed using oil-basedemulsions prepared with an Arab Medium crude oil. Synthetic brine wasprepared by adding 3.5% weight/volume (w/v) of sodium chloride (NaCl) todeionized water. Emulsions were formed by adding 20% volume (vol.) ofsynthetic brine and 80% vol. of crude oil and mixing for 40 seconds at16,400 rpm with a T-25 ULTRA-TURRAX® homogenizer manufactured by IKA® ofStaufen, Germany. The volume of emulsion used for each experiment was500 millimeters (ml). As discussed below, in some experiments, 40parts-per-million (ppm) of demulsifier were added to the crude oil priorto the mixing. In such experiments, the demulsifier type was theincumbent demulsifier used at the production site of the tested crudeoil. Fluids were preheated to 45° C., and the experiments were conductedat a temperature of 45° C. Likewise, the separation curves of thesamples previously exposed to the electric field were obtained in anoven set at a temperature of 45° C.

In each experiment, the applied electric field was 4.8kilovolts/centimeter (kV/cm). The electric field was generated acrosselectrodes spaced at 3.34 cm by applying a voltage of 16 kV. Thewaveform was sinusoidal with a frequency of 1 kilohertz (kHz). However,it should be appreciated that embodiments of the disclosure are notlimited to the characteristics of the electric fields described in theexperiments. For example, it should be appreciated that an optimizationof the electric field characteristics may be performed for each crudeoil quality. For example, the electric field intensity could range fromfew tens of volts/centimeter (V/cm) up to the point of incipientelectrical discharge or droplet break-up. As will be furtherappreciated, the waveform used to generate the electric field may bebased on a mathematical function optimized to sustain an optimalelectric field amplitude while preventing short circuiting of theelectrodes. The frequency may be optimized as discussed in more detailin below.

Base Case—Horizontal Flow and No Electric Field

The Arab Medium crude oil used in the experiments is known to formextremely stable emulsions. To set a baseline, some experiments wereconducted in the absence of any electric field by circulating a sampleof the Arab Medium crude oil emulsion through a Type A flow conditionerand an empty pipe (Type C), with and without the injection of ademulsifier (that is, the demulsifier dosage being either 40 ppm or 0ppm). The percentage of the total water volume in the initial emulsionsample that segregated after a given separation time was measured todetermine the separation performance. The volume percentage of waterseparated from the emulsion samples at time periods of 0 minute (min), 5min, 10 min, 20 min, and 25 min was determined for a flow rate of about0.4 liter/minute (l/min) (that is, about 12.3 seconds residence time).Table 1 depicts the results of the base case experiments for eachcombination of flow conditioner (Type A or Type C) and demulsifierdosage (0 ppm or 40 ppm):

TABLE 1 VOL. PERCENTAGE OF WATER SEPARATED VS. TIME FOR BASE CASESeparation Type-A Type-A Type C Type C time (0 ppm (40 ppm (0 ppm (40ppm (min) demulsifier) demulsifier) demulsifier) demulsifier)  0 0% 0.4%0% 1.1%  5 0% 0.9% 0% 2.2% 10 0% 1.3% 0% 2.8% 20 0% 1.7% 0% 3.3% 25 0%2.2% 0% 3.9%

FIG. 1 is a graph 100 of volume percentage of water separated vs.separation time after electrocoalescence (EC) illustrating the resultsof the base case experiments for each combination of flow conditioner(Type A or Type C) and demulsifier dosage (0 ppm or 40 ppm). As shownFIG. 1, the y-axis 102 depicts volume percentage of water separated andthe x-axis 104 depicts separation time. FIG. 1 also includes an insetgraph 106 with different intervals on the y-axis 102 and x-axis 104 tofurther illustrate the results of the base case experiments.

Configuration 1: Horizontal Flow and Short Flow Conditioners

In the first configuration, experiments were conducted using Arab Mediumcrude oil emulsions flowing in the horizontal direction. The emulsionswere formed with the Arab Medium crude oil with the addition of 40 ppmof demulsifier. The experiments were performed using each of the Type A,Type B, and Type C flow conditioners oriented horizontally. A flow rateof 0.4 l/min was used in all the experiments, which corresponds to aresidence time in the applied electric field of about 12 seconds. Hereagain, the percentage of the total water volume in the initial emulsionsample that segregated after a given separation time was measured todetermine the separation performance. The volume percentage of waterseparated from the emulsion samples at time periods of 0 minutes (min),5 min, 10 min, 20 min, and 25 min was determined. Two runs of the Type Cflow conditioner were performed. Table 2 depicts the results of firstconfiguration experiments for each flow conditioner (Type A, Type B orType C):

TABLE 2 VOL. PERCENTAGE OF WATER SEPARATED VS. TIME FOR FIRSTCONFIGURATION Type C (40 ppm Separation time Type-A (40 ppm Type-B (40ppm Type C (40 ppm demulsifier), 2nd (min) demulsifier) demulsifier)demulsifier) run  0 40% 30%  7.5% 7.5%   5 80% 60%   25% 25% 10 85% 65%32.5% 35% 20 85% 70%   40% 45% 25 85% 70%   40% 45%

FIG. 2 is a graph 200 of volume percentage of water separated vs.separation time after EC illustrating the results of the firstconfiguration experiments for each flow conditioner (Type A, Type B, orType C). As shown FIG. 2, the y-axis 202 depicts volume percentage ofwater separated and the x-axis 204 depicts separation time.

The results shown in Table 2 and FIG. 2 illustrate the performances ofthe flow conditioners and demonstrate the importance of their geometryfor enhancing phase separation. The Type A flow conditioner provided thehighest separation performance and improved water separation to over 80%in 10 minutes. The Type B flow conditioner had the next highestseparation performance, allowing a separation of 65% of the water in 10minutes. The two runs performed with the Type C flow conditioner (emptypipe) show separation performances which approach 35% of resolved waterin 10 minutes.

Experiments were also performed using the first configuration and ahigher flowrate, to evaluate the combined effect of higher turbulenceand shorter residence time in the electric field region. The experimentswere conducting using the Type A and Type C flow conditioners at aflowrate of 0.8 l/min determining an average flow velocity twice as fastas the previous first configuration experiments, at about 2.3 cm/s. Thevolume percentage of water separated from the emulsion samples at timeperiods of 0 minutes (min), 5 min, 10 min, 20 min, and 25 min wasdetermined. Table 3 depicts the results of first configurationexperiments at the higher flow rate and Type A and Type C flowconditioners:

TABLE 3 VOL. PERCENTAGE OF WATER SEPARATED VS. TIME FOR FIRSTCONFIGURATION AT HIGHER FLOW RATE Separation time Type-A Type-C (min)(40 ppm demulsifier) (40 ppm demulsifier)  0 15%  7.5%  5 30% 12.5% 1035%   15% 20 40% 22.5% 25 45%   25%

FIG. 3 is a graph 300 of volume percentage of water separated vs.separation time after EC illustrating the results of the firstconfiguration experiments at the higher flowrates for the Type A andType C flow conditioners. As shown FIG. 3, the y-axis 302 depicts volumepercentage of water separated and the x-axis 304 depicts separationtime.

As shown in Table 3 and FIG. 3, the separation performance decreases ascompared to the lower flowrate used to produce the results shown inTable 2 and FIG. 2. After 10 minutes of separation, the separationperformance decreases by 59% for the Type A flow conditioner and by 55%for the Type C flow conditioner. By using twice as long flowconditioners, the separation performance decrease was demonstrated to beprimarily attributed to the shorter residence time of the emulsionsunder the electric field.

Configuration 2: Vertical Flow and Short Flow Conditioner

In the second configuration, experiments were conducted using ArabMedium crude oil emulsions flowing in the horizontal direction. Theemulsions were formed with the Arab Medium crude oil with the additionof 40 ppm of demulsifier. The second configuration experiments wereconducted to demonstrate the applicability of the disclosure via theintegration of electrodes in the downward (that is, vertical) leg ofindustrial separator inlet devices. As a result, embodiments of thedisclosure may have applications in the integration within separatorinlet devices, such that the use of electric field is synergized withthe flow turbulence existing in such devices.

The experiments were performed using Type A and Type C flow conditionersoriented vertically. A feedstream flow rate of 0.4 l/min was used, withthe downward velocity was determined by gravity. Here again, thepercentage of the total water volume in the initial emulsion sample thatsegregated after a given separation time was measured to determine theseparation performance. The volume percentage of water separated fromthe emulsion samples at time periods of 0 minutes (min), 5 min, 10 min,20 min, and 25 min was determined. Two runs of the Type C flowconditioner were performed. Table 4 depicts the results of firstconfiguration experiments for each flow conditioner (Type A or Type C):

TABLE 4 VOL. PERCENTAGE OF WATER SEPARATED VS. TIME FOR SECONDCONFIGURATION Separation time Type-A (40 ppm Type-C (40 ppm (min)Control demulsifier) demulsifier)  0 0% 15%  7.5%  5 0% 30% 12.5% 10 0%35%   15% 20 0% 40% 22.5% 25 0% 45%   25%

FIG. 4 is a graph 400 of volume percentage of water separated vs.separation time after EC illustrating the results of the secondconfiguration experiments for the Type A and Type C flow conditioners.As shown FIG. 4, the y-axis 402 depicts volume percentage of waterseparated and the x-axis 404 depicts separation time.

The relatively low separation performance was a result of the shortresidence time in the electric field. However, Table 4 and FIG. 4 showan improvement in separation performance using the Type A flowconditioner as compared to the Type C flow conditioner.

Configuration 3: Horizontal Flow and Longer Flow Conditioner

In the third configuration, experiments were conducted using Arab Mediumcrude oil emulsions flowing in the horizontal direction in flowconditioners longer than the flow conditioners used in the firstconfiguration. The experimental results of the second configurationsuggested that higher flowrates may lead to inefficient waterseparation. The third configuration experiments were conducted todetermine whether the performance decrease using the secondconfiguration was due to excessive turbulence inside the flowconditioners or from shorter residence time in the electric field.

The emulsions were formed with the Arab Medium crude oil with theaddition of 40 ppm of demulsifier. The experiments were performed usingthe Type A, Type B, and Type C flow conditioners oriented horizontallyand with a length twice as long as the flow conditioners used in thefirst configuration. A flow rate of 0.8 l/min was used in all theexperiments to replicate the 2.3 cm/s emulsion flowing velocity used inthe first configuration experiments that produced the results shown inTable 3. Consequently, the emulsion residence time under the electricfield was increased from about 6.6 seconds up to about 13.9 seconds,while the mechanical mixing energy per unit time was the same.

The percentage of the total water volume in the initial emulsion samplethat segregated after a given separation time was measured to determinethe separation performance. The volume percentage of water separatedfrom the emulsion samples at time periods of 0 minutes (min), 5 min, 10min, 20 min, and 25 min was determined. Two runs of the Type C flowconditioner were performed. Table 5 depicts the results of the thirdconfiguration experiments for each flow conditioner (Type A, Type B, andType C):

TABLE 5 VOL. PERCENTAGE OF WATER SEPARATED VS. TIME FOR THIRDCONFIGURATION Separation Type C (40 ppm time Type-A (40 ppm Type B (40ppm demulsifier), (min) Control demulsifier) demulsifier) 2nd run  0 0%58.8% 30% 24%  5 0% 88.2% 45% 40% 10 0% 94.1% 60% 52% 20 0% 94.1% 65%60% 25 0% 94.1% 70% 60%

FIG. 5 is a graph 500 of volume percentage of water separated vs.separation time after EC illustrating the results of the thirdconfiguration experiments for each flow conditioner (Type A, Type B, orType C). As shown FIG. 5, the y-axis 502 depicts volume percentage ofwater separated and the x-axis 504 depicts separation time.

As shown in Table 5 and FIG. 5, the separation performance issignificantly increased. The water separation obtained using the Type Aflow conditioner approaches 100%. The results of the third configurationexperiments illustrate the importance of selecting an optimal residencetime and the synergistic effect of static flow conditioners and anelectric field.

The experimental results support two additional conclusions. First, evenat a greater flow rate, the flow conditioners do not offset the effectof the electric field by breaking up the water droplets after thecoalescence events. Second, the geometry of the flow conditioner may bea primary factor in the separation performance. For example, based onthe experimental results, the type B flow conditioner consistentlyprovided a separation performance that was between the Type C (emptypipe) flow conditioner and Type A flow conditioner. In another example,the Type A flow conditioner provided the best separation performance forall experiments and conditions.

Electrohydrodynamic Dimensionless Numbers

For certain embodiments (such as, for example, relatively largerindustrial systems), a range for the electroviscous number (Nev) wasdetermined from the experimental results described above. Nev may bedefined as the ratio of the dielectric electric Rayleigh number (Ra) andmay provide a quantification of the dominance of electrostatic forcesover kinetic forces. Nev may be determined according to Equation 1:

$\begin{matrix}{N_{ev} = \frac{Ra}{Re}} & (1)\end{matrix}$

Where Ra and Re are determined according to Equations 2 and 3:

$\begin{matrix}{{Ra} = \frac{\epsilon_{0}E_{0}^{2}L^{2}}{\rho \cdot v^{2}}} & (2) \\{{Re} = \frac{L_{m} \cdot U_{0}}{v}} & (3)\end{matrix}$

Where ρ is the fluid density in kilograms/meters³ (kg/m³), ν is thekinematic viscosity in meters/seconds (m²/s), ∈₀ is the vacuumpermittivity in farads/meter (F/m), L_(m) is the system characteristiclength in meters (m), L is the flow conditioner length in meters (m), E₀is the electric field in volts/meter (V/m), and U₀ is the average fluidvelocity in meters/seconds (m/s).

Solving Equations 1-3 using the experimental data results in anidentification of an electroviscous number Nev in the range of 1000 to600000. Thus, an Nev in the range of 1000 to 600000 may be used for thepreliminary design of a separation apparatus in accordance with theembodiments described in the disclosure. As will be appreciated, suchsystems may be effective as long as the electric field E is below acritical value E_(max) that leads to the onset of droplets breakup. Thevalue of E_(max) may vary between emulsions but, in some embodiments,may be set at E_(max)=6 kilovolts/centimeter (kV/cm) based on possibleinter-droplet field intensification phenomena. Further, in someembodiments, L_(m) should not exceed 2 cm to provide for an efficientdroplet collision process.

Optimizing the Electric Field and Coalescence Forces

As will be appreciated, various techniques are known (such as, forexample, the Lichtenecker equation) for the determination of thedielectric properties of a mixture of oil and water according to theirrelative proportions, dielectric constants, and the temperature (whichhas a particular effect on the water phase dielectric constant). Usingthe Lichtenecker equation, the variation of the dielectric properties ofan oil-water mixture was evaluated for a water content in the range of0% to 40% and a temperature in the range of 20° C. to about 60° C. Table6 depicts the % variation of the dielectric constant of the oil-watermixture at various water contents and temperatures, with respect to thepermittivity of pure oil at 20° C. (assumed to be 2.5):

TABLE 6 VARIATION OF DIELECTRIC CONSTANT (PERMITTIVITY) OF WATER-OILMIXTURE WITH WATER CUT AND TEMPERATURE % variation of % variation of %variation of dielectric dielectric dielectric constant constant constantWater content (20° C.) (40° C.) (60° C.)  5  15%  15%  15% 10  33%  32% 32% 15  54%  53%  53% 20  80%  79%  78% 25 112% 110% 108% 30 151% 148%145% 35 198% 194% 189% 40 257% 250% 243%

As shown in Table 6, the variation of the oil-water mixture dielectricconstant is not negligible, and a greater water content results in agreater temperature effect on the dielectric constant. Consequently,because real-world production environments typically involve bothfluctuating temperature and water content over time (for example, as aresult of the temperature difference between daytime and nighttime), thevariation of the dielectric constant may be significant and may affectthe performance of electrocoalescers. As discussed below, the simulationresults described in the disclosure demonstrate that a change indielectric properties of this magnitude may have a negative effect onthe electric field distribution and result in a decrease in performanceof an electrocoalescer system. However, existing electrocoalescersystems fail to account for these effects of variation of dielectricproperties in fluids. In contrast, however, embodiments described in thedisclosure may detect these variations and minimize their impact on theseparation performance of an electrocoalescer system.

Moreover, the dielectric properties of the flowing medium (for example,a water-in-oil emulsion) effect the efficiency of the electrocoalescenceprocess. The dielectric constant of a water-in-oil emulsion depends onthe water-to-oil volume ratio and the water salinity. FIG. 6 is a graph600 of the permittivity of a water-in-oil emulsion vs frequencyillustrating the frequency-dependent behavior of the dielectric constantof the water-in-oil emulsion. As shown FIG. 6, the left y-axis 602depicts the permittivity value and the x-axis 604 depicts the frequencyin hertz (Hz). As also shown in FIG. 6, the right y-axis 606 depicts theloss factor value (e″). The permittivity is depicted by line 608 in FIG.6, and the loss factor is depicted by line 610 in FIG. 6.

FIG. 7 is a graph 700 of permittivity vs. frequency for a water-in-oilemulsion that depicts the effect of the water cut on the permittivity.As shown FIG. 7, the y-axis 702 depicts the permittivity value and thex-axis 704 depicts the frequency in hertz (Hz). As also illustrated inFIG. 7, line 706 depicts the permittivity of a water-in-oil emulsionhaving a 10% water cut, line 708 depicts the permittivity of awater-in-oil emulsion having a 20% water cut, and line 710 depicts thepermittivity of a water-in-oil emulsion having a 40% water cut. FIG. 7also depicts line 712 corresponding to the permittivity of an exampleflow conditioner.

The dielectric constant of a water-in-oil emulsion depend on variablessuch as temperature, water salinity, water content and crude oilcomposition, all of which may have an impact on electrocoalescence. Forexample, the flow conditioner embedded into an electrocoalescence systemwas assumed to have a permittivity which, at the working frequency of 1kHz, matched (that is, was equal to) the permittivity of a flowingemulsion with 10% water cut. At this condition, corresponding to point A(714) in FIG. 7, electrocoalescence efficiency may be maximized.Moreover there is no difference in the permittivities of thewater-in-oil emulsion and the flow conditioner.

As will be appreciated, as an oil reservoir ages, more water iscoproduced with the crude oil. Additionally, to guarantee a homogeneousexploitation of the reservoir, production wells are used in differentcombinations, as determined by the reservoir engineers. As a result, theproduction facility receiving the well streams may experience frequentvariations in the water cut in the received streams. As shown in FIG. 7,an increase in the water cut may affect the emulsion permittivity with atranslation of the permittivity curve for a water-in-oil emulsion to theleft and upward, as shown by line 708 to line 710, and by line 710 toline 712). As illustrated in FIG. 7, this translation identifies a newoperating condition at point A′ (716), and then at point A″ (718) as thewater cut increases.

The following paragraphs describe how a change in the emulsiondielectric properties affects the separation efficiency of existingelectrocoalescer systems by modifying the electric field inside thefluid volume of the electrocoalescer system.

A computational simulations study was conducted using the COMSOLMultiphysics scientific software package. As discussed below, thesimulation showed that a difference between dielectric constants of theflow conditioner material and the flowing medium will lead to electricfield inhomogeneities that are proportional to the difference indielectric constants.

Table 7 provides a quantification of this effect and shows the impact ofthe relative permittivity ratio εr_(emulsion)/εr_(conditioner) on themaximum (Emax) and minimum (Emin) electric fields in the fluid domain.

TABLE 7 EFFECT OF RELATIVE PERMITTIVITY RATIO ON MAXIMUM AND MINIMUMELECTRIC FIELDS εr_(emulsion)/εr_(conditioner) |Emax| (kV/cm) |Emin|(kV/cm) 1/6  43%  20% 1/5  39%  19% 1/4  33%  18% 1/3  26%  17% 1/2  17% 13% 1    0%  0% 2   −18% −22% 3   −30% −35% 4   −39% −45% 5   −45% −52%6   −50% −57%

The computer simulations were run assuming a constant flow conditionerpermittivity of 2.5 and an average electric field of 1.6 kV/cm. Toperform the simulations, the geometry of flow conditioner Type A used inthe experiments described above was created numerically, and then theelectric field was computed in the fluid volume flowing through the flowconditioner. In order to remove edge effects and be as conservative aspossible, the results were obtained for an inner square section of thefluid domain, with square length equal to half of the internal diameterof the flow conditioner.

FIG. 7 shows that a water-in-oil emulsion having a 40% water cut (line710) has a permittivity of 11 at frequencies in the range of about 100hertz up to about 100,000 hertz (that is, frequencies commonly used inelectrocoalescers). Consequently, in this example, the permittivityratio is about 4.4 (water-in-oil emulsion permittivity/flow conditionerpermittivity=11/2.5). As shown in Table 7, this permittivity ratio willresult in a variation of the maximum and minimum electric fieldsintensity of about −39% and about −45% respectively of the expectedvalue. As will be appreciated, this is a significant reduction in theelectric field and may have dramatic negative effect on theelectrocoalescer efficiency, as the dipolar force driving the dropletsattraction in the electrocoalescer is proportional to the second powerof the electric field intensity.

Separation Apparatuses with Adaptive Permittivity Flow Conditioners

As discussed herein, embodiments of the disclosure advantageously have aflow conditioner that adapts its permittivity to the permittivity of theflowing medium (for example, a water-in-oil emulsion). Advantageously,as shown in Table 7, ensuring that the permittivity of the flowconditioner is equal to (for example, 1:1) or as similar as possible tothe permittivity of the flowing medium minimizes the variation in themaximum and minimum electric fields intensity and resulting negativeimpact on separation performance. In view of the foregoing, embodimentsof the disclosure that implement adaptive permittivity flow conditionersin a separation apparatus are described below.

FIG. 8 depicts a separation apparatus 800 having a series of flowconditioners 802 constructed from materials having differentpermittivities and disposed in a series of sections 804 of the apparatus800 in accordance with an embodiment of the disclosure. The apparatusmay include a measurement section 806, dielectric constant measurementdevice 808, an AC voltage generator 810, and a section selector 812. Insome embodiments, the sections of the separation apparatus 800 may begenerally cylindrical (for example, tubular) shaped. As described below,the separation apparatus 800 may measure the dielectric constant of aflowing medium in the measurement section 806 and select one of the flowconditioners 802 that has a permittivity closest to the permittivity ofthe flowing medium.

As shown by arrow 814, an emulsion may enter the measurement section 806of the separation apparatus 800. The dielectric constant measurementdevice 808 may measure the dielectric properties of the flowing mediumand transmit the permittivity to the section selector 812. The sectionselector may be powered by the AC voltage generator 810. In response tothe permittivity of the flowing medium received from the dielectricconstant measurement device 808, the section selector 812 may energizethe electrode of the section 804 having the flow conditioner with apermittivity that is equal to or as similar as possible to thepermittivity of the flowing medium. As used herein, the term “as similaras possible to” refers to a flow conditioner permittivity that is asclose as possible in value to the permittivity of the flowing medium asis achievable by the physical properties of the flow conditionermaterials. For example, in some embodiments of the separation apparatus800, the permittivity of a selected flow conditioner may be within athreshold difference of the permittivity of the flowing medium. In someembodiments, the threshold difference may be less than 1%, less than 2%,less than 3%, less than 4%, or less than 5%.

The section selector 812 may include logic to compare a receivedmeasured permittivity to a list of stored permittivities. In someembodiments, the section selector 812 may include anapplication-specific integrated circuit (ASIC) or a field-programmablegate array (FPGA). In some embodiments, the section selector 812 mayinclude a microprocessor, such as a reduced instruction set computing(RISC) processor or a complex instruction set computing (CISC)processor. The section selector 812 may include volatile memory, such asrandom access memory (RAM), and non-volatile memory, such as ROM, flashmemory, any other suitable optical, magnetic, or solid-state storagemedium, or a combination thereof. The memory may store a list ofpermittivities associated with the flow conditioners 802. The memory maystore an identifier or other indicator associated with each permittivity(for example, in a list or other data structure) that indicates theappropriate signal for energizing the electric field of a flowconditioner associated with the permittivity.

Each of the sections 804 may include one or more electrodes forgenerating an electric field in that section for electrocoalescence inthe flowing medium. As shown in FIG. 8, the three flow conditioners 802may each have a different permittivity. For example, the flowconditioner 802A disposed in section 804A may have a first permittivity,the flow conditioner 802B disposed in section 804B may have a secondpermittivity different from the first permittivity, and the flowconditioner 802C disposed in section 804C may have a third permittivitydifferent from the first and second permittivity. In one example, aflowing medium in the measurement section 806 may have a measurementpermittivity that mostly closely matches the first permittivity of theflow conditioner 802A. In this example, the section selector 812 wouldenergize the electrode in the section 804A having the flow conditioner802A. The electrodes in sections 804B and 804C would not be energizedand, consequently, no electric field would be generated in thosesections. In another example, a flowing medium in the measurementsection 806 may have a measurement permittivity that mostly closelymatches the permittivity of the flow conditioner 802C. In this example,the section selector 812 would energize the electrode in the section804C having the flow conditioner 802C. The electrodes in sections 804Aand 804B would not be energized and no electric field would be generatedin those sections.

The flow conditioners 802 may have varying permittivity by usingdifferent dielectric materials to construct the flow conditioner. Insome embodiments, a dielectric material of a given permittivity may beformed from the insertion of an inorganic filler into a polymericmatrix. For example, in some embodiments the first flow conditioner 802Amay have a first inorganic filler in a first polymeric matrix, thesecond flow conditioner 802B may have a second inorganic filler in asecond polymeric matrix, and the third flow conditioner 802C may have athird inorganic filler in a third polymeric matrix. In some embodiments,the inorganic filler may be Al₂O₃, BaTiO₃, TiO₂, or ZrO₂. As will beappreciated, the amount and type of inorganic filler to be added to thepolymeric matrix may be adjusted to produce a material having thedesired dielectric properties. Additionally, it should be appreciatedthat the polymeric matrix may be selected having relatively low waterand crude oil uptake (as compared to other matrices) to minimize changesin the dielectric constant of the flowing medium. Table 8 depictsexample inorganic fillers and example polymers that may be used toconstruct a flow conditioner suitable for use with embodiments of thedisclosure:

TABLE 8 EXAMPLE FLOW CONDITIONER MATERIALS Permittivity Permittivity(dielectric (dielectric Inorganic filler constant) Polymer constant)TiO₂ 100 Polyimide 2.8-3.2 Neoprene  78 Fluorinated polyimide 2.5-2.9Al₂O₃ 9-10 Methylsilsesquioxane 2.6-2.8 SiO₂ 3.9 Polyarelene ether2.6-2.9 BaTiO₃ 1200-10000 Polyethylene 2.3-2.7 ZrO₂  22 Polystyrene2.5-2.9 Teflon AF 2.1

For example, in some embodiments, the flow conditioners 802 may beconstructed from BaTiO₃, TiO₂, or ZrO₂ in a polyimide matrix.

In other embodiments, the flow conditioners 802 may be constructed usinga ceramic material having closed cell porosity. In some embodiments inwhich the flowing medium includes sand particles, flow conditionersconstruction using a ceramic material may be used to minimize erosioncaused by the sand particles.

One or more of the flow conditioners 802A, 802B, and 802C may eachinclude a static mixer having a highly branched geometry or a helicoidalgeometry. In some embodiments, one or more of the flow conditioners802A, 802B, and 802C may be a straight pipe without a static mixer. Insome embodiments, the flow conditioners 802A, 802B, and 802C may havedifferent geometries. For example, the flow conditioners 802A and 802Bmay have a static mixer with a highly branched geometry and the flowconditioner 802C may have a static mixer with a helicoidal geometry. Inother embodiments, the flow conditioners 802A, 802B, and 802C may eachinclude other flow conditioner elements, such as guide vanes and mixers.In other embodiments, the flow conditioner 802 may have four flowconditioners or more, arranged in series in the flow direction or inparallel.

In some embodiments, the electric field and length of each of the flowconditioners 802A, 802B, and 802C may be selected to ensure that the Nevof the flow conditioner is in the range of about 1000 to about 600000.In some embodiments, the electric field of each of the flow conditioners802A, 802B, and 802C may be, for example, about 6 kilovolts/centimeter(kV/cm). In some embodiments, the characteristic mixing length L_(m) ofeach of the flow conditioners 802A, 802B, and 802C may be 2 cm or less.

The separation apparatus 800 may be used in a horizontal orientation ora vertical orientation or in any intermediate inclination. Theseparation apparatus 800 may be used in a horizontal orientation or avertical orientation. In embodiments in which the separation apparatusis installed in a vertical or inclined orientation, the flow through theseparation apparatus 800 may be upward (that is, against gravity) ordownward (that is, with gravity). In some embodiments, the separationapparatus 800 may be included in an inlet of a separator vessel, such asseparator vessel in a crude oil processing facility. For example, theseparation apparatus 800 may be integrated into an inlet of a highpressure production trap (HPPT), an inlet of a low pressure productiontrap (LPPT), or both. In some embodiments, the separation apparatus 800may be additionally or alternatively be located between a high pressureproduction trap (HPPT) and a low pressure production trap (LPPT). Insuch embodiments, the separation apparatus 800 may enable the removal ofwater from crude oil before the crude oil is provided to a wet crudehandling train of a crude oil processing facility. Advantageously, theuse of the separation apparatus 800 in a crude oil processing facilitymay improve water separation, reduce the consumption of a demulsifier,reduce capital costs for additional water separation, and reduce heatingrequirements (for example, the crude oil may typically be heated toenhance separation using existing separation technologies).

In some embodiments, the separation apparatus 800 may be integrated intoan inlet device, such as a multi-drum inlet device or a separator inletdevice, such as be retrofitting the separation apparatus 800 to anexisting inlet device. For example, the separation apparatus 800 may addelectrocoalescence separation to existing inlet devices, includingdevices that already have a type of separation capability.

FIG. 9 depicts a process 900 for operation of the separation apparatus800 depicted in FIG. 8 in accordance with an embodiment of thedisclosure. Initially, the flow of a water-in-oil emulsion through theseparation apparatus 800 may be initiated (block 902). For example, thewater-in-oil emulsion may be produced crude oil from a well or multiplewells that is transported to a crude oil processing facility. Thedielectric properties of the water-oil-emulsion in the measurementsection may be measured (block 904).

The measured permittivity may be sent to the section selector 812 (block906). The section selector 812 may compare the measured permittivity tostored permittivities associated with the flow conditioners in theseparation apparatus and select the flow conditioner permittivity thatis equal to or is as similar as possible to the measured permittivity ofthe water-in-oil emulsion. (block 908). For example, for an embodimenthaving three flow conditioners, the permittivity of one of the threeflow conditioners that is as similar as possible to the measuredpermittivity may be selected. Next, the electrodes of the flowconditioner having the selected flow conditioner permittivity may beenergized to generate an electric field (block 910), and thewater-in-oil emulsion may be separated in the section having theelectric field and selected flow conditioner (block 912).

FIG. 10 depicts a separation apparatus 1000 having a flow conditioner1002 constructed from a material having a frequency-dependent dielectricresponse (that is, frequency-dependent permittivity) and disposed in asection 1004 of the apparatus 1000 in accordance with an embodiment ofthe disclosure. The apparatus may include a measurement section 1006, adielectric constant measurement device 1008, an AC voltage generator1010, and a frequency selector 1012. In some embodiments, the sectionsof the separation apparatus 1000 may be generally cylindrical (forexample, tubular) shaped. As described below, the separation apparatus1000 may measure the dielectric constant of a flowing medium in themeasurement section 1006 and select a frequency of the generatedelectric field in the section 1004 to match the frequency-dependentpermittivity of the flow conditioner 1002 with the permittivity offlowing medium.

As shown by arrow 1014, a water-in-oil emulsion may enter themeasurement section 1006 of the apparatus 1000. The dielectric constantmeasurement device 1008 may measure the dielectric properties of theflowing medium and transmit the permittivity to the frequency selector1012. The section selector may be powered by the AC voltage generator1010. In response to the permittivity of the flowing medium receivedfrom the dielectric constant measurement device 1008, the frequencyselector 1012 may select an electric field frequency that causes thepermittivity of the flow conditioner to be equal to or as similar aspossible to the permittivity of the emulsion. The frequency selector1012 then energizes the electrodes (via the AC voltage generator 1010)of the flow conditioner at the selected frequency.

The frequency selector 1012 may include logic to compare the measuredpermittivity to a range of permittivities achievable by the flowconditioner 1002. Each compare a received measured permittivity to alist of stored permittivities. In some embodiments, the frequencyselector 1012 may include an application-specific integrated circuit(AISC) or a field-programmable gate array (FPGA). In some embodiments,the frequency selector 1012 may include a microprocessor, such as areduced instruction set computing (RISC) processor or a complexinstruction set computing (CISC) processor. The frequency selector 1012may include volatile memory, such as random access memory (RAM), andnon-volatile memory, such as ROM, flash memory, any other suitableoptical, magnetic, or solid-state storage medium, or a combinationthereof. The memory may store, for example, a range of permittivitieseach associated with a frequency (such as a list or other datastructure) or an algorithm that enables calculation of the frequencyfrom a permittivity.

In some embodiments, the flow conditioner 1002 may be constructed from amaterial having a dielectric permittivity that varies with frequency ofthe electric field. In some embodiments, the material may be a polymericmaterial having silica nanoparticles in an epoxy resin. As will beappreciated, materials having a dielectric permittivity that varies withfrequency may be manufactured in the range of frequencies used inelectrocoalescers for separation of oil-water mixtures. For example, theamplitude of the permittivity change and the frequency at which itoccurs may be adjusted by the selection of the matrix and fillers withconsideration of their respective dielectric permittivities andelectrical conductivities.

In some embodiments, the electric field and length of the flowconditioner 1002 may be selected to ensure that the Nev of the flowconditioner is in the range of about 1000 to about 600000. In someembodiments, the electric field of the flow conditioner 1002 may be atmost about 6 kilovolts/centimeter (kV/cm). In some embodiments, thecharacteristic mixing length L_(m) of the flow conditioner 1002 may be 2cm or less.

The flow conditioner 1002 may include a static mixer having a highlybranched geometry or a helicoidal geometry. In some embodiments, theflow conditioner 1002 may be a straight pipe without a static mixer. Inother embodiments, the flow conditioner 1002 may include other flowconditioner elements, such as guide vanes and mixers.

The separation apparatus 1000 may be used in a horizontal orientation ora vertical orientation or at any intermediate inclination. Inembodiments in which the separation apparatus is installed in a verticalor inclined orientation, the flow through the separation apparatus 100may be upward (that is, against gravity) or downward (that is, withgravity). In some embodiments, the separation apparatus 1000 may beincluded in an inlet of a separator vessel, such as separator vessel ina crude oil processing facility. For example, the separation apparatus1000 may be integrated into an inlet of a high pressure production trap(HPPT), an inlet of a low pressure production trap (LPPT), or both. Insome embodiments, the separation apparatus 1000 may be additionally oralternatively be located between a high pressure production trap (HPPT)and a low pressure production trap (LPPT). In such embodiments, theseparation apparatus 1000 may enable the removal of water from crude oilbefore the crude oil is provided to a wet crude handling train of acrude oil processing facility. Advantageously, the use of the separationapparatus 1000 in a crude oil processing facility may improve waterseparation, reduce the consumption of a demulsifier, reduce capitalcosts for additional water separation, and reduce heating requirements(for example, the crude oil may typically be heated to enhanceseparation using existing separation technologies).

In some embodiments, the separation apparatus 1000 may be integratedinto an inlet device, such as a multi-drum inlet device or a separatorinlet device, such as be retrofitting the separation apparatus 1000 toan existing inlet device. For example, the separation apparatus 1000 mayadd electrocoalescence separation to existing inlet devices, includingdevices that already have a type of separation capability.

FIG. 11 is a graph 1100 of permittivity vs. frequency for a water-in-oilemulsion that depicts a frequency shift and effect on permittivity inaccordance with an embodiment of the disclosure. FIG. 11 reproduces thegraph 700 shown in FIG. 7 and discussed above. As shown in FIG. 11, they-axis 1102 depicts the permittivity value and the x-axis 1104 depictsthe frequency in hertz (Hz). As also illustrated in FIG. 11, line 1106depicts the permittivity of a water-in-oil emulsion having a 10% watercut, line 1108 depicts the permittivity of a water-in-oil emulsionhaving a 20% water cut, and line 1110 depicts the permittivity of awater-in-oil emulsion having a 40% water cut. FIG. 11 also depicts line1112 corresponding to the permittivity of an example flow conditioner.

As shown in FIG. 11, after moving from the optimal condition depicted bypoint A (1114) to the point A′ (1116), a frequency adjustment from kHzto 300 Hz would increase the permittivity of the flow conditioner (shownin line 1112) and move to the optimal condition shown by point B (1118).

FIG. 12 depicts a process 1200 for operation of the separation apparatus1000 depicted in FIG. 10 in accordance with an embodiment of thedisclosure. Initially, the flow of a water-oil-emulsion through theseparation apparatus 1000 may be initiated (block 1202). For example,the water-in-oil emulsion may be produced crude oil from a well ormultiple wells that is transported to a crude oil processing facility.The dielectric properties of the water-oil-emulsion in the measurementsection may be measured (block 1204).

The measured permittivity may be sent to the frequency selector 1012(block 1206). Using the measured permittivity, the frequency selector1012 may select a frequency of the electric field so that thefrequency-dependent permittivity of the flow conditioner 1002 is equalto or as similar as possible to the measured permittivity. For example,in some embodiments, the frequency selector 1012 may compare themeasured permittivity to a range of permittivities achievable by theflow conditioner 1002. Each permittivity in the range of permittivitiesmay be associated with a frequency, such as via a stored list, analgorithm that enables calculation of the frequency from a permittivity,or other technique. Next, the frequency selector may change the electricfield frequency of the flow conditioner to the selected frequency (thatis, changing the frequency via the signal sent to the electrodes), suchthat the permittivity of the flow conditioner changes in response to theselected frequency to be equal to or as similar as possible to thepermittivity of the emulsion (block 1208). The water-oil emulsion may beseparated in the section having the electric field and flow conditionerwith matching permittivity (block 1210).

FIGS. 13A and 13B depict a separation apparatus 1300 having replaceableflow conditioners 1302 and 1304 constructed from different materialshaving different permittivities and disposed in a section 1306 of theapparatus 1300 in accordance with an embodiment of the disclosure. Theapparatus may include a measurement section 1308, a dielectric constantmeasurement device 1310, and an AC voltage generator 1312. In someembodiments, the sections of the separation apparatus 1300 may begenerally cylindrical (for example, tubular) shaped. In someembodiments, the dielectric constant measurement device 1310 may becoupled to a computer 1314. As described below, the separation apparatus1300 may measure the dielectric constant of a flowing medium in themeasurement section 1308 and provide an indication if the dielectricconstant of the flowing medium differs by an unacceptable amount fromthe permittivity of the flow conditioner in the section 1306. Inresponse, the flow conditioner (e.g., flow conditioner 1302) in theseparation apparatus 1300 may be replaced with another flow conditioner(e.g., flow conditioner 1304). As will be appreciated, although theembodiment shown in FIGS. 13A and 13B depict two flow conditioners,other embodiments may use three, four, five or more flow conditionersthat may each be removable and installable in the separation apparatus1300.

As shown by arrow 1316, an emulsion may enter the measurement section1308 of the apparatus 1300 having the flow conditioner 1302. Thedielectric constant measurement device 1310 may measure the dielectricproperties of the flowing medium and compare the permittivity of theflowing medium to the permittivity of the flow conditioner 1302. Inresponse to the comparison, as shown in FIG. 13B, the flow conditioner1302 may be replaced by the flow conditioner 1304 that more closelymatches the permittivity of the flowing medium. In some embodiments, thesection 1306 may include an access panel, a removable wall, or otherfeature that enables access to a flow conditioner disposed in thesection. In this manner, the flow conditioner 1302 may be removed andthe flow conditioner 1304 may be installed in the section 1306.

The flow conditioners 1302 and 1304, and other flow conditioners used inthe separation apparatus 1300, may have different permittivities byusing different dielectric materials to construct the flow conditioner.In some embodiments, a dielectric material of a given permittivity maybe formed from the insertion of an inorganic filler into a polymericmatrix. In some embodiments, the inorganic filler may be Al₂O₃, BaTiO₃,TiO₂, or ZrO₂. As will be appreciated, the amount and type of inorganicfiller to be added to the polymeric matrix may be adjusted to produce amaterial having the desired dielectric properties. Additionally, itshould be appreciated that the polymeric matrix may be selected havingrelatively low water and crude oil uptake (as compared to othermatrices) to minimize changes in the dielectric constant over time andwhen exposed to fluids. Table 8 described above provides examples ofinorganic materials and polymers. For example, in some embodiments, theflow conditioners 1302 and 1304 may be constructed from BaTiO₃, TiO₂, orZrO₂ in a polyimide matrix.

In other embodiments, the flow conditioners for use in the separationapparatus 1300 may be constructed using a ceramic material having closedcell porosity. For example, in some embodiments, the first flowconditioner 1302 may have a first inorganic filler in a first polymericmatrix, and the second flow conditioner 1304 may have a second inorganicfiller in a second polymeric matrix. In some embodiments in which theflowing medium includes sand particles, flow conditioners constructionusing a ceramic material may be used to minimize erosion caused by thesand particles.

In some embodiments, the electric field and length of each of the flowconditioners 1302 and 1304 may be selected to ensure that the Nev of theflow conditioner is in the range of about 1000 to about 600000. In someembodiments, the electric field of each of the flow conditioners 1302and 1304 may be at most about 6 kilovolts/centimeter (kV/cm). In someembodiments, the characteristic mixing length L_(m) of each of the flowconditioners 1302 and 1304 may be 2 cm or less.

One or more of the flow conditioners 1302 and 1304 may each include astatic mixer having a highly branched geometry or a helicoidal geometry.In some embodiments, one or more of the flow conditioners 1302 and 1304may be a straight pipe without a static mixer. In some embodiments, theflow conditioners 1302 and 1304 may have different geometries. Forexample, the flow conditioners 1302 may have a static mixer with ahighly branched geometry and the flow conditioner 1304 may have a staticmixer with a helicoidal geometry. In other embodiments, the flowconditioners 1302 and 1304 may include other flow conditioner elements,such as guide vanes and mixers.

The separation apparatus 1300 may be used in a horizontal orientation ora vertical orientation or at any intermediate inclination. In someembodiments, the separation apparatus 1300 may be included in an inletof a separator vessel, such as separator vessel in a crude oilprocessing facility. For example, the separation apparatus 1300 may beintegrated into an inlet of a high pressure production trap (HPPT), aninlet of a low pressure production trap (LPPT), or both. In someembodiments, the separation apparatus 1300 may be additionally oralternatively be located between a high pressure production trap (HPPT)and a low pressure production trap (LPPT). In such embodiments, theseparation apparatus 1300 may enable the removal of water from crude oilbefore the crude oil is provided to a wet crude handling train of acrude oil processing facility. Advantageously, the use of the separationapparatus 1300 in a crude oil processing facility may improve waterseparation, reduce the consumption of a demulsifier, reduce capitalcosts for additional water separation, and reduce heating requirements(for example, the crude oil may typically be heated to enhanceseparation using existing separation technologies).

In some embodiments, the separation apparatus 1300 may be integratedinto an inlet device, such as a multi-drum inlet device or a separatorinlet device, such as be retrofitting the separation apparatus 1300 toan existing inlet device. For example, the separation apparatus 1300 mayadd electrocoalescence separation to existing inlet devices, includingdevices that already have a type of separation capability.

FIG. 14 depicts a process 1400 for operation of the separation apparatus1300 depicted in FIGS. 13A and 13B in accordance with an embodiment ofthe disclosure. Initially, the flow of a water-oil-emulsion through theseparation apparatus 1300 may be initiated (block 1402). For example,the water-in-oil emulsion may be produced from crude oil from a well ormultiple wells that is transported to a crude oil processing facility.The dielectric properties of the water-oil-emulsion in the measurementsection may be measured (block 1404).

The measured permittivity may be provided, such as on a display of acomputer coupled to the separation apparatus (block 1406). Based on themeasured permittivity and the permittivity of the flow conditionerinstalled in the separation apparatus, the flow conditioner may bereplaced with a flow conditioner having a permittivity that is equal toor as similar as possible to the measured permittivity of the emulsion(block 1408). After replacement, the electrodes of the flow conditionermay be energized and the water-in-oil emulsion may be separated in thesection having the electric field and flow conditioner with equal orsimilar permittivity (block 1410).

Ranges may be expressed in the disclosure as from about one particularvalue, to about another particular value, or both. When such a range isexpressed, it is to be understood that another embodiment is from theone particular value, to the other particular value, or both, along withall combinations within said range.

Further modifications and alternative embodiments of various aspects ofthe disclosure will be apparent to those skilled in the art in view ofthis description. Accordingly, this description is to be construed asillustrative only and is for the purpose of teaching those skilled inthe art the general manner of carrying out the embodiments described inthe disclosure. It is to be understood that the forms shown anddescribed in the disclosure are to be taken as examples of embodiments.Elements and materials may be substituted for those illustrated anddescribed in the disclosure, parts and processes may be reversed oromitted, and certain features may be utilized independently, all aswould be apparent to one skilled in the art after having the benefit ofthis description. Changes may be made in the elements described in thedisclosure without departing from the spirit and scope of the disclosureas described in the following claims. Headings used or described in thedisclosure are for organizational purposes only and are not meant to beused to limit the scope of the description.

What is claimed is:
 1. A method of separating a mixture of two liquids,comprising: providing the mixture to a separation apparatus, theapparatus comprising: a permittivity measurement apparatus configured tomeasure the permittivity of the mixture; a flow conditioner sectioncomprising an electrode for generating an electric field and a flowconditioner having a permittivity range, the permittivity rangecomprising a function of a frequency of the electric field; and afrequency selector configured to receive the mixture permittivity fromthe permittivity measurement apparatus and energize at least one firstelectrode of the flow conditioner section at a frequency; measuring thepermittivity of the mixture; comparing the mixture permittivity to thepermittivity range to make a comparison; energizing the electrode of theflow conditioner section at a selected frequency based on the comparisonbetween the mixture permittivity and permittivity range; and directingthe mixture through the electric field.
 2. The method of claim 1,wherein the mixture is a water-in-oil emulsion.
 3. The method of claim1, wherein the flow conditioner comprises a helicoidal-shaped flowconditioner comprises a helicoidal flow path or a branched flowconditioner comprising a plurality of branched flow paths.
 4. The methodof claim 1, comprising transmitting the mixture permittivity to afrequency selector configured to receive the mixture permittivity fromthe permittivity measurement apparatus and energize the electrode of theflow conditioner section at the frequency.